In the medical device field, many devices are designed to provide a practitioner with access through the skin of a patient. In order to provide this access, the devices often incorporate some sort of "sharp". Exemplary of these devices are scalpels, hypodermic syringe needles, catheter placement needles and the like. Both catheter placement needles and hypodermic syringe needles are necessarily elongate, slender and very sharp. Most of these needles are intended for only a single use, and once used for their intended purpose are considered hazardous to anyone who may have reason to encounter them, including the practitioner who is using the device, those assisting the practitioner and any support staff who may be involved in the ultimate disposal of the devices. The hazards related to used "sharps" medical devices are well reported and need not be further dwelt upon here.
There are many products, both patented and unpatented, that are available to practitioners and support staff to assist in the handling and disposal of such sharps. Additionally, there continues to be a need for controlling the disposal of used hypodermic syringes and needles to prevent their salvage and reuse by users of intravenous illicit drugs. Initial efforts to protect practitioners and support staff from used needles included devices to cut off needles, various kinds of receptacles for receiving and disposing of sharps. More recently, specialized shielding devices and retractable needles have been disclosed. Early examples of the efforts in retractable needles as applied to syringes are provided by Allard, et al. in U.S. Pat. Nos. 4,838,863 and 4,838,869.
U.S. Pat. No. 4,838,863 discloses a hypodermic syringe with an cylindrical outer body adapted to accept a smaller fluid storage within the inner walls thereof that has a removable cap on one end of the cylinder for providing access to insert and remove vial. The disclosed syringe further includes a spring loaded double headed needle that is held in place by a retainer until the storage vial has been punctured by the end of the needle, the vial filled and removed. The needle is then retracted into the space vacated by the vial.
U.S. Pat. No. 4,838,869 discloses a retractable hypodermic needle configured for one-time use wherein the needle is spring loaded and automatically irretrievably retracted into the hypodermic syringe when the syringe plunger is fully depressed, whereby protrusions on the end of the plunger engage tabs holding the spring loaded needle to release the needle for retraction. Since hypodermic syringes are used for many different procedures, a syringe that has a needle that automatically retracts once the plunger is depressed and withdrawn, a hypodermic syringe based on the disclosure of this patent may not be suitable for many procedures.
A series of patents to Kulli, beginning with U.S. Pat. No. 4,747,831 that discloses a cannula insertion set with a safety retracting needle, provide practitioners with a needle that is selectively retractable. The '831 patent discloses a cannula insertion needle that projects forward from a hollow handle. The needle has a selectively releasable latch that retains the needle in the projecting forward position against a biasing spring. The hollow handle includes a chamber that is sized to allow the needle to be completely withdrawn into the chamber by the spring when the practitioner releases the latch. In a subsequent disclosure, U.S. Pat. No. 4,927,414, Kulli discloses a syringe having a barrel with a hollow elongate chamber, surrounded by a plunger for drawing and dispensing liquids. The disclosed syringe has a needle projecting outwardly that is selectively releasable into the hollow chamber when the practitioner has completed the desired procedure. The syringe disclosed in this procedure is complex, having many parts, and a commercial product based on this disclosure has never been produced. Another disclosure by Kulli, U.S. Pat. No. 4,900,307 discloses syringe needle that includes a hub with a chamber similar to that disclosed in the 4,747,831 patent for the insertion. A syringe manufactured according to the disclosure in the '307 patent, while satisfactory for some procedures, would retain a substantial volume of undeliverable medicament, "dead space", and no successful commercial product based on this disclosure is available. The Kulli disclosures contain additional references and descriptions of other retractable needle devices that provide additional background related to the area of protected needle devices.
As illustrated by the above references, there is recognition in the medical device field of the desirability of a hypodermic needle that provides the practitioner and support staff with protection from inadvertent exposure to a used sharp point of a needle. While the referenced disclosures address some of the needs, none of them have resulted in commercially successful hypodermic syringes. If a hypodermic syringe were available that had substantially no more dead space than conventional commercial syringes, had a needle that was selectively releasable by the practitioner and additionally, was not as complex, thus facilitating its manufacture, the art of hypodermic syringes would be advanced. A further benefit would be realized if the syringe was able to accept several different sized needles. Such a hypodermic syringe and needle is disclosed hereinbelow.